O'Fallon, MO
Long-term air quality
What this page tells you
This page combines annual PM2.5, unhealthy days, 5-year trend, and data coverage so you can compare long-term air quality, not just today's reading.
O'Fallon, MO air quality summary: O'Fallon, MO holds a clean air score of 70.5 and a grade of B. The annual mean PM2.5 concentration is 8.3 µg/m³. O'Fallon has an annual mean PM2.5 level of 8.3 µg/m³, representing moderate long-term exposure. The long-term air quality in O'Fallon has been improving over recent years.
Clean Air Score
A clean air score of 70.5 and a grade of B reflect a generally healthy long-term air quality environment. This indicates that pollution levels are typically within acceptable limits for the area's residents.
🏡 What This Means for Buying
The improving trend in air quality is a positive environmental indicator for long-term residency in O'Fallon. Prospective residents should consider this data as part of a comprehensive community evaluation.
Indoor Air Quality in O'Fallon, MO
Outdoor pollution can still affect indoor air when windows are open, filtration is weak, or wildfire smoke moves in.
How to react when today's AQI changes
Use the AQI bands below to decide whether to open windows, run an air purifier, or stay indoors when pollution spikes in O'Fallon.
AQI 0-50
GoodOpen windows: Open windows if you want fresh air.
Air purifier: No purifier needed for most homes.
Indoor activity: Normal indoor activity is fine.
AQI 51-100
ModerateOpen windows: Sensitive groups should limit open-window time.
Air purifier: Use fans or filtration if dust or pollen is bothering you.
Indoor activity: Most people can stay active indoors.
AQI 101-150
Unhealthy for Sensitive GroupsOpen windows: Keep windows closed.
Air purifier: Run a HEPA purifier in the main room and bedroom.
Indoor activity: Sensitive groups should reduce outdoor exposure.
AQI 151+
UnhealthyOpen windows: Keep windows and doors closed.
Air purifier: Run HEPA continuously and seal obvious drafts.
Indoor activity: Stay indoors as much as possible; use an N95 if you must go out.
Common indoor air concerns in O'Fallon:
- Seasonal pollen and dust mite allergens
- VOCs from household products
Recommended action: If today's AQI reaches 101 or higher, close windows and run HEPA filtration before indoor air starts to feel smoky or stale.
Top Products for O'Fallon Homes:
🩺 My Health Risk Assessment
See how O'Fallon's air quality affects you and your family specifically.
Health Advice
Good for most outdoor activities.
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</> Create Free Widget🏡 Property Value Impact Analysis
Between 2019 and 2024, O'Fallon's air quality improved by 1.1 μg/m³. Based on NBER studies, this change correlates with a estimated 4.4% increase in relative property value retention.
Cleaner Alternatives in MO
Why O'Fallon earned a 70.5
Raw inputs, scoring weights, and data coverage for this city.
Best Time to Run
Find the cleanest hours for your run today.
Cycling Forecast
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📅 Past 30 Days Trend
Real-time daily PM2.5 AQI
🌸 Pollen Outlook
Current Seasonal Forecast
How it worksBased on current seasonal forecast data. Not a long-term pollution rating or relocation score.
Score Breakdown
| Component | Weight | Score Contribution |
|---|---|---|
| Annual Air Quality | 40% | 53.2 |
| Unhealthy Days | 25% | 100 |
| 5-Year Trend | 20% | 55.5 |
| Seasonal Variability | 10% | 92.4 |
| Extreme Events | 5% | 100 |
Explore More Air Quality Data
Frequently Asked Questions
About This Data
Data Sources
Historical air quality mapping and scoring are based completely on official U.S. Environmental Protection Agency (EPA) AirNow API data. 5-day AQI forecasts are provided by WAQI.
Methodology
Our Clean Air Score (0-100) is a proprietary algorithm that weighs multiple factors:
- Annual PM2.5 averages (40%)
- Frequency of unhealthy days (25%)
- 5-year pollution trends (20%)
- Seasonal variability and extreme events (15%)
Updates & Accuracy
Real-time data is updated hourly. Historical aggregate scores are recalculated monthly to reflect the latest trends. While we strive for accuracy, sensor maintenance and local conditions can affect individual readings.
Practical Advice
When AQI > 100: Sensitive groups (children, elderly, asthmatics) should limit prolonged outdoor exertion.
When AQI > 150: Everyone should avoid outdoor exercise and keep windows closed.
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O'Fallon Air Quality FAQs
Is O'Fallon a good fit for people who care about long-term air quality?
O'Fallon, MO is a suitable choice with a clean air score of 70.5 and a grade of B. Its PM2.5 annual mean of 8.3 µg/m³ indicates a generally favorable long-term environment.
How often does O'Fallon experience unhealthy air or high pollution exposure?
O'Fallon maintains 0% unhealthy air days, consistent with its grade of B. This suggests residents are rarely exposed to elevated pollution spikes throughout the year.
Is air quality in O'Fallon improving or getting worse over time?
Air quality in O'Fallon is on an improving trend, showing positive long-term environmental shifts in the area.
Does air quality vary across different parts of the city?
Air quality can vary within the city due to local traffic, industry, and location patterns, especially given the distance to the proxy monitor source.